Re: Need a Comparator that will ignore glitches

On Fri, 12 Jan 2007 05:25:31 -0800, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:



Vcc
k = ln -----------
Vcc - Vth


Arbitrarily setting R1 equal to R2 will make Vth half of Vcc so, if
Vcc is 5V, Vth will be equal to 2.5V. Then:


5V
k = ln ----------- ~ 0.92
5V - 2.5V


---
Oops...

k = ln 2 ~ 0.69

Now, since:


T = k Rt Ct,


if we arbitrarily choose Ct as being 0.1µF and use the OP's 100ms
delay we can rearrange to solve for Rt:


T 0.1s
Rt = -------- = -------------- ~ 1.1 megohms.
k * Ct 0.92 * 1e-7F


---
Oops...

0.1s
Rt = --------------- ~ 1.5 megohms
0.69 * 1E-7F


--
JF
.